Joan Rivers didn’t sign off on the throat procedure she underwent from an unauthorized doctor the day she suffered heart and respiratory failure, according to the New York Daily News.

A doctor with Rivers’ entourage, who reportedly wasn’t authorized to work at the clinic at which Rivers’ was being examined, performed an unplanned biopsy on her vocal cords that caused the comedian to stop breathing, a medical source told the newspaper.

The newspaper reported that medical experts said such a procedure isn’t supposed to be performed outside of a hospital.

The Aug. 28 procedure at Yorkville Endoscopy — a clinic that usually only deals with digestive issues — caused Rivers’ vocal cords to seize. It’s a condition called a laryngospasm, and it cut off Rivers’ air supply.

“A biopsy like that should only be done in a hospital setting,” the source reportedly said. “If she had been in a hospital when it happened, she might have been OK.”

According to the medical source, who was reportedly briefed on the case, Rivers’ doctor — who identified himself as an ear, nose and throat specialist — asked to use their instruments when the clinic’s doctor noticed “something” on Rivers’ vocal cords.

“He asked and they let him,” the source said. “A huge no-no.”

Rivers reportedly signed off on an endoscopy, not the far more dangerous biopsy of her vocal cords.

A representative for Rivers declined comment. A spokeswoman for Yorkville Endoscopy said patient confidentiality laws prevented her from commenting.

A rep for the clinic told ABC News last week the clinic is “a federally and state licensed facility, has the same level of life-saving and resuscitation devices (such as state-of-the-art cardiac defibrillators, airway management equipment, etc.) found in any hospital emergency room or hospital-based operating room.”

Maybe not.

The spokesperson added, “Yorkville Endoscopy has performed 18,000 procedures since it opened in February 2013. Yorkville Endoscopy has maintained an exceptional safety record that far exceeds the national average.”

They might want to recheck those numbers now.

Rivers was rushed to the hospital after she stopped breathing. Doctors put the “Fashion Police” star in a medically-induced coma. She died at Sept. 4 at Mount Sinai Hospital in New York City.

An autopsy was inconclusive and more tests are being done to determine Rivers’ cause of death.

State health officials said last week they are taking a closer look at the Upper East Side clinic.

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